AAMOF
As A Matter Of Fact
AFAICR
As Far As I Can Remember
AFAICT
As Far As I Can Tell
AFAIK
As Far As I Know
ASAP
As Soon As Possible
ATM
At The Moment
AWGTHTGTATA
Are We Going To Have To Go Through All This Again?
AWGTHTGTTA
Are We Going To Have To Go Through This Again?
BAC
By Any Chance
BBFN
Bye Bye For Now
BCNU
Be Seeing You
BFN
Bye For Now (an Internet abbreviation)
BIOYIOP
Blow It Out Your Input Output Port
BK
Because
BRB 
Be Right Back (generally used on chat systems)
BTA
But Then Again
BTSOOM
Beats the **** out of me
BTW
By The Way
BYKT
But You Knew That
BYKTA
But You Knew That Already
CMIIW
Correct Me If I'm Wrong
CUL
See You Later
CU L8R
See You Later
CYA
Cover Your ****
CYL
See You Later
DIIK
Damned If I Know
DILLIGAFF
Do I Look Like I Give a Flying Filament
DLG
Devilish Little Grin
DNPM
Darn Near ****** Myself
DOM
Dirty Old Man
EOD
End Of Discussion
EOL
End Of Lecture
EOT
End Of Thread
ESOSL
Endless Snorts of Stupid Laughter
FDROTFL
Falling Down Rolling On The Floor Laughing
FITB
Fill In The Blank....
FOTCL
Falling Off The Chair Laughing
FTF
Face to face, as opposed to screen-to-screen interaction
FWIW
For What It's Worth
FYI
For Your Information
GD&R
Grin, Duck & Run
GIWIST
Gee I Wish I'd Said That
GLG
Goofy Little Grin
GOK
God Only Knows
GOTFIA
Groaning On The Floor In Agony
IAC
In Any Case
IAE 
In Any Event
IIRC
If I Recall Correctly
IITYWYBAD
If I Tell You, Will You Buy Another Drink
IITYWYBMAB
If I Tell You, Will You Buy Me A Beer
IMCDO
In My Conceited Dogmatic Opinion.
IMCO
In My Considered Opinion
IMHO
In My Humble Opinion
IMNSHO
In My Not So Humble Opinion
IMO
In My Opinion
INPO
In No Particular Order
IOW
In Other Words
IRL
In real life (as opposed to Net.life)
ISTR
I seem to recall
KCBIWIYWI
Keep Coming Back, It Works If You Work It
KISS
Keep It Simple Stupid
LLTA
Lots and Lots of Thunderous (or Thundering) Applause
LMAO
Laughing My **** Off
LOL
Laughing out loud
LTMSH
Laughing 'Til My sides Hurt
MORF
Male Or Female
MUNG
Mash Until No Good
NBL
Not Bloody Likely
NICBDAT
Nothing Is Certain But Death And Taxes
NIMBY
Not In My Backyard
NIMTO
Not In My Term of Office
NPLU
Not People Like Us
NQOS
Not Quite Our Sort
NRN
No Reply Necessary
OIC 
OH!, I See
OTOH
On The Other Hand
OTT
Over The Top
PF&HOMW
Printed, Framed & Hanging On My Wall
PGY
Post Graduate year PGY-1, PGY-2 etc. used in PGY Med.
PITA
Pain In The ****
PMETC
Pardon Me Etc.
PMJI
Pardon My Jumping In
PMYMHMMFSWGAD
Pardon Me, You Must Have Mistaken Me For Someone Who Gives A Damn.
POV
Point Of View
PPL
People
PTO
Patent and Trademark Office (US Govt)
ROFL
Rolling On Floor Laughing
ROFLAHMSL
Rolling On Floor Laughing And Holding My Sides Laughing
ROFLASC
Rolling On The Floor Laughing And Scaring Cat.
ROFLASTC
Rolling On The Floor Laughing And Scaring The Cat.
ROTBA
Reality On The Blink Again
ROTFL
Rolling On The Floor Laughing
ROTFLMAAOBPO
Rolling On The Floor Laughing My A*** And Other Body Parts Off
ROTM
Right On The Money
ROY G. BIV
An acronym for the colors of the spectrum
RSN
Real Soon Now
RTFM
Read The ******* Manual
SITD
Still in the dark
SOP
Standing Operational Procedures
SWAG
Simple Wild **** Guess
SYT
Sweet Young Thing
TANJ
There Ain't No Justice
TANSTAAFL
There Ain't No Such Thing As A Free Lunch
TBH
To Be Honest
TIA
Thanks In Advance
TIC
Tongue In Cheek
TINALO
This Is Not A Legal Opinion
TINAR
This Is Not A Recommendation
TIWTGLGG
This Is Where The Goofy Little Grin Goes
TJATAW
Truth, Justice, And The American Way
TLA
Three Letter Acronym
TPTB
The Powers That Be
TRDMC
Tears Running Down My Cheeks
TTBOMK
To The Best Of My Knowledge
TTFN
Ta Ta For Now
TTYL
Talk To You Later
TYVM
Thank You Very Much
WAMKSAM
Why Are My Kids (or Kitties) Staring At Me?
WIBAMU
Well I'll be a Monkey's Uncle
WRT
With regard to
WYSBYGI
What You See Before You Get It
WYSIWYG
What You See Is What You Get.
WYTYSYDG
What You Thought You Saw, You Didn't Get
YAFA
Yet Another ******* Abbreviation
YAP
Yet Another Ploy
YMMV
Your Mileage May Vary
HTH
Hope That Helps
HWGA
Here We Go Again